Ore mill



C. 0. SMITH March 30, 1943.

ORE MILL Filed Oct. 3, 1941 5 Sheets-Sheet 1 ATTORNEYS C. 0. SMITH March 30, 1943.

ORE MILL Filed Oct. 3, 1941 5 Sheets-Sheet 2 0 SMITH INVENTOR.

E D Y L C ATTORNEYS C. 0. SMITH March 30, 1943.

ORE MILL Filed Oct. 3, 1941 INVENTOR.

CLYDE 0. SMITH ATTORNEYS Patented Mar. 30, 1943 I UNITED STATES PATENT OFFICE 7 Claims.

' taining metal therefrom. More specifically, this invention relates to mills or classifiers used for obtaining valuable precious metals from the ground ore, and this invention is concerned particularly with that type of mills known as ball mills.

In such mills the grinding of the ore or quartz is done by means of steel balls placed with the material to be ground inside a rotating cylinder, the cylinder being supported for rotation on a horizontal axis. The ore and water are fed into the cylinder at one end and small particles of the metal, together with the crushed ore and mud, pass through a screen or slots at the other end of the cylinder after the grinding. From the finely ground ore or mud the particles of metal are then recovered by washing, the metal particles, which are heavier than the finely crushed ore, being held in the bottoms of troughs by means of battles, etc., or in other suitable settling pans or receptacles, the finely ground ore or mud being finally washed away.

It is quite important in this process that particles of the metal which become loosened from the ore during the grinding should not be subjected to any more grinding than necessary, since any further grinding of the metal particles will result in some of the metal being ground to a powder fineness with the result that this is apt to be washed away and lost. For this reason the discharge openings at the end of the revolving cylindrical grinder should be made large enough to permit fairly large particles of loosened metal to pass through, but when this is done some are will also pass through the openings which will require further grinding before all the metal obtainable from this ore is recovered. These larger particles of ore should therefore be returned to the grinder for further grinding.

The object of this invention is to provide an improved and more emcient means for separating out the dislodged particles of metal from the ore and for further treating those particles of ore which require additional grinding and finally, when necessary, returning such particles of ore to the cylindrical grinder.

A further object of this invention is to provide for a more effective washing of the ore after it first leaves the grinder and before it is returned for further grinding, and also to provide more eflicient means for handling the ore which requires regrinding.

advantages are attained in my improved ore mill will be briefly described in the following specification in which reference is to be had to the accompanying drawings. In the drawings:

, Figure 1 is a longitudinal section or sectional side elevation of an ore mill or ball mill embodying my invention;

Figure 1A is a transverse section corresponding to the line IA-|A of Figure 1;

Figure 2 is a transverse section taken on line 22 of Figure 1 looking in the direction of the arrows; I

Figure 3 is a sectional perspective view of the feeding cone of the special ore handling means of my invention;

Figure 4 is an end elevation of the entire device;

Figure 5 is a longitudinal section of the return feeder showing the means for returning the ore which is to be ground; and

Figure 6 is a sectional perspective view of part of the return feeder of Figure 5. a

In Figure 1, A indicates a rotating cylindrical 5 chamber, of the type common to ball mills, into which the ore to be ground is fed at one end. The ore passes into the chamber through the axially aligned tubular channel I2, The ore is delivered into this tubular channel I! by means of a hollow curved feeding arm I I-, which, as the entire device rotates, picks up the ore and water from a trough l0, lifting the mixture which has been picked up until the mixture slides down thearm I l into the tubular channel l2.

The shape of the feeding arm II will be seen in Figure 1A. The feeding arm II and tubular channel I! are integral with, or rigidly attached to, the corresponding end wall of the body l3 0f the cylindrical grinding chamber A and thus rotate with the apparatus. This end of the apparatus is journaled within a suitable supporting bearing M.

The opposite end wall l5 of the cylindrical chamber A carries an annular grating or screened discharge outlet l6, formed preferably of radially arranged slots l6 (Figure 2). -As indicated in Figure 1, the particles of ore and metal, when ground sufliciently to pass through these slots, are thus discharged from the grinding chamber A. The apparatus so far described is similar to that commonly found in ore grinders of this type.

Attached to the discharge end of the cylindrical body l3 and thus located on the outside of the end wall l5 of the chamber A are a plurality The manner in which these objects and other of radially located compartments l8. The number of these compartments, as shown in Figure 2, is six in the apparatus illustrated, although this number of course may be varied. A mesh screen l1 forms the outer circumferential wall of these compartments. The compartments are divided from each other by the radial partitions or walls 26 (Figure 2) and the remaining walls of the compartments include two frustro-conical surfaces 2| and 22, located and arranged as shown in Figure 1, together with the annular grating l6.

A'second tubular channel or transfer member IS, in axial alignment with the cylinder chamber A and tubular channel I2, is formed integrally with, or rigidly attached to, the end wall I! of the chamber A and the frustro-conical walls 2| and 22. This tubular member I3 is :Iournaled in a suitable bearing 20, similar to bearing l4, and provides the support for this end of the apparatus.

Openings 2! are provided in the tubular member I! where the walls of the compartments I3 converge near the axis, one opening 23 being provided for each compartment and this opening thus comprising the final outlet port for the compartment for the ore carried in it which is too large to pass through the circumferential mesh screen ll. Further openings 23 are provided in the tubular member l3 near the end wall I; of the grinding chamber, for a purpose which will be explained later.

A central pipe or tubular core 23 extends through the tubular member l3. At the right end of the apparatus, as viewed in Figure 1, this pipe or core extends beyond the tubular member l9 and is connected by suitable means (not shown) with a source of water supp y. The inner end of the pipe 23, is left open in order to permit water to pass freely through the pipe as indicated by the arrows in Figure 1. The frustro-conical wall 2| is provided with small holes 30 (Figure 1) near its juncture with the wall I! of the cylindrical chamber A, and the water from pipe 23 passes through the openings 23 at the end of member I3 and through the holes 30, as shown, and mixes with the ore particles as they leave the grinding chamber A and pass on to the mesh screen l1, thus providing desired additional washing of the ground ore. I have found this additional supply of water delivered at this stage to be very important in properly facilitating the washing and screening of the ore and metal particles.

On the pipe core 23, and integral therewith, is a discharge deflecting cone B which is positioned below the openings or ports 25, as shown in Figure 1. The construction of this discharge defleeting cone element will be seen more clearly in Figure 3. This element includes a conical surface 32, a circular end wall 3| which extends slightly beyond the conical surface to form the annular flange 3|, and a plurality of radially disposed fins 33. The fins 33 are preferably equal in number to, and in radial alignment with, the partition walls 23 between the compartments |3. The diameter of the end wall 3| corresponds to the internal diameter of the tubular member Hi. The fins 33 extend to the wall of the surrounding member IS. A ring 34 crosses the outer ends of the fins transversely near the apex end of the conical wall 32, the outer diameter of this ring corresponding to the interior diameter of the member Is.

As will be apparent from Figure l, the purpose of the discharge deflecting cone B is to cause the ore particles which pass out from the bottom of each compartment l3 through the discharge outlet 23 to be pushed to the right along the inside of the tubular member l3. The flange 3| of the end wall 3| prevents these particles from escaping to the left when entering the member is. The ring 34 permits the particles, as they enter the member l9 from a top compartment, to move along to the right under the ring, but this ring prevents the ore particles at the bottom of member l3 from sliding back towards the left (as viewed in Figure 1) and thus escaping through a lower opening 23 into a lower compartment l8.

At the outside end of the tubular member I! large discharge ports 35 are providedthroughwhich all the ore particles which have passed along the tubular member I3 are finally discharged. A trough or box 3.8 is located beneath these final outlet ports 35; The bottom of this trough or box 38 slopes downwardly, as shown in Fig. 4, so that particles of metal, which might have become dislodged meanwhile from the pieces of ore or rock subjected to this subsequent treatment, will slide downwardly on the bottom until reaching the discharge trap 31 from which such particles, together with some of the mud," are then directed over settling troughs or similar devices (not shown) in which the metal particles will be allowed to settle and collect in the usual manner while the fine ore or "mu is finally washed, away. For the same purpose a collecting vessel 5| is placed below the circular mesh screen I I in order to collect the material which passes through screen H, which collected material at that point is similarly passed over settling troughs or other devices (not shown).

The rest of the ore, discharged from the tubular member l3, must be subjected to further grinding and therefore should be returned to the grinding chamber A. For this purpose I provide means for returning such ore to the grinding chamber and this means will now be explained. I

A return feeder, designated as a whole by the reference character C, includes a hollow shaft 43 of fairly substantial diameter mounted for rotation on an axis parallel to, but at a higher level than, the axis of the grinding apparatus. A pair of hollow arms 38 and 39, preferably shaped in the form of an involute curve, as shown in Figure 4, are rigidly mounted on the shaft 4|) and discharge into this shaft through suitable oppositely arranged openings 42 (Figure 5). Thus as the shaft 4|) and its connected arms rotate, each arm in turn dips into the trough 36, picks up some of the ore from this trough and, as the arm is raised, slides this picked up ore down into the shaft 40.

A deflector 4| (see Figures 5 and 6) is provided at the end of the hollow shaft 4|). This deflector 4| has a cylindrical end 43 which forms the closure for that end of the hollow shaft 43. The other end of this deflector is formed into a pair of deflecting surfaces 44 by having two opposite sides cut away obliquely so as to form a V. These deflector surfaces extend between the openings 42 and serve to prevent the ore particles, delivered from one feeding arm, from passing down into the other feeding arm.

The hollow rotating shaft 4|) is preferably fiared at the left hand end or discharge end 52, as shown in Figures 1 and 5, and discharges into a chute 53 which delivers the ore by gravity to theinitial trough Hi. When the ore has been delivered to the trough II from the chute '8, it is then in position to renew its journey through the grinding mill.

The hollow shaft 40 is Journaled forrotation shaft 46 and a belt 50 connects this pulley with a pulley 48 mounted on the pipe or tubular core 28, so that rotation of the grinder produces rotation of the return feeding means C. Rotation of the grinder may be produced by any suitable means (not shown), such means being common with "ball mills.

Thus in my device special provision is made to prevent unnecessary grinding of the ore or metal particles and thus to minimize the loss of metal particles due to their being reduced to powder form. Unlike some of the ball" mills now in general use, the ore particles which are too large to pass through the mesh screen I! are not returned directly to the initial grinding chamber A, but are passed on in the apparatus in the manner explained and the oversize particles or rejects from the screen I! are then finally returned to the feed box of the mill. Because of the method and means which I employ of returning such screen rejects to the initial feed box of the grinder or mill-that is, the returning of these outside of the mill or grinder itself--it is possible and feasible to install supplementary concentrating devices, such as jigs, traps, amalgamation plates etc., in closed circuit thereby saving considerable of the metal particles before they are ground so flne as to make recovery diflicult, if not impossible.

Minor changes would of course be possible in the apparatus which I have shown for carrying out my invention, without departing from the principle of my invention. The particular apparatus described I have found very efllcient and satisfactory for attaining the objects which I have in mind. It is not my intention, however, to limit my invention otherwise than is set forth in the claims.

I claim:

1. In an ore mill of the character described, a rotatable grinder, discharge openings at the discharge end of said grinder, compartments on the discharge end of said grinder, said compartments connected with said grinder by said openings, a peripheral screen extending about said compartments, means located below said screen for collecting ore particles passing through said screen, a central member attached in axial alinement with said grinder extending from said end of said grinder and rotated with said grinder, a discharge port in each compartment connecting with the interior of said central member, whereby ore particles which are too large to pass through said peripheral screen will be discharged into said central member, means preventing ore in said central member from discharging back into said grinder from the adjacent end of said central member, a discharge opening at the opposite end of said central member remote from said grinder, means for collecting ore from said discharge opening of said central member and for separating ofi larger particles of ore for return to said grinder.

2. In an ore mill of the character described, a rotatable grinder, discharge openings at the discharge end of said grinder, radially-arranged compartments on the discharge end of said grinder, said compartments connected with said grinder by said openings, a peripheral screen extending about said compartments, means located below said screen for collecting ore particles passing through said screen, a central transfer member extending from said end of said grinder, a discharge port in each compartment connecting with the interior of said transfer member, whereby ore particles which are too large to pass through said peripheral screen will be discharged into said transfer member, means in said transfer member cooperating with said ports to direct material entering therethrough away from said compartments and from said grinder, a discharge opening at the opposite end of said transfer member remote from said grinder, means for collecting ore from said discharge opening of said transfer member and for separating of! larger particles of ore for return to said grinder.

3. In an ore mill of the character described, a rotatable grinder, discharge openings at the discharge end of said grinder, radially-arranged compartments on the discharge end of said grinder, said compartments connected with said grinder by said openings, a peripheral screen extending about said compartments, a tubular member attached to and in axial alinement with said grinder extending from said end of said grinder, a discharge port in each compartment connecting with the interior of said tubular member, whereby ore particles which are too large to pass through said peripheral screen will be discharged into said tubular member, a discharge deflector in said tubular member cooperating with said ports to direct material entering therethrough away from said compartments and from said grinder, a water pipe in said tubular member, said pipe having a discharge end located between said discharge deflector and said grinder, means for delivering water into said compartments from said pipe, a discharge opening at the opposite end of said tubular memberremote from said grinder, means for collecting ore from said discharge opening of said tubular member and for separating off larger particles of ore for return to said grinder.

4. In an ore mill of the character described, a rotatable grinder, discharge openings at the discharge end of said grinder, radially-arranged compartments on the discharge end of said grinder, said compartments connected with said grinder by sa d openings, a frustro-conical wall centrally located on the discharge end of said grinder and extending beyond said grinder with the larger diameter end adjacent the grinder, said frustro-conicai wall constituting one of the walls of said compartments, a peripheral screen extending about said compartments, a tubular member attached to and in axial alinement with said grinder extending from said end of said grinder, a discharge port in each compartment connecting with the interior of said tubular member, whereby ore particles which are too large to Pass through said peripheral screen will be discharged into said tubular member, a deflecting cone in said member cooperating with said ports to direct material entering therethrough away from said compartments and from said grinder, a water pipe extending longitudinally in said tubular member, said pipe having a discharge and located between said deflecting cone and said grinder, openings in said tubular member and in said frustro-conical wall permitting water from said pipe to pass into said compartments, 9, discharge opening at the opposite end of said tubular member remote from said grinder, means for collecting ore from said discharge opening or said tubular member and for separating of! larger particles of ore for return to said grinder.

5. In an ore mill of the character described, a rotatable grinder, discharge openings at thedischarge end of said grinder, radially-arranged compartments on the discharge end of said grinder, said compartments connected with said grinder by said openings, a frustro-conical wall centrally located on the discharge end of said grinder and extending beyond said grinder with the larger diameter end adjacent the grinder, said irustroconical wall constituting one of the walls of said compartments, a peripheral screen extending about said compartments, means located below said screen for collecting ore particles passing through said screen, a tubular member attached to and in axial alinement with said grinder extending from said end of said grinder, a discharge port in each compartment connecting with the interior of said tubular member, whereby ore particles which are too large to pass through said peripheral screen will be discharged into said tubular member, a discharge deflector in said tubular member cooperating with said ports to direct material entering therethrough away from said compartments, said discharge deflector including a conical surface, the apex of said conical surface extending away from said compartments and grinder, radial veins on said conical surface, a water pipe extending longitudinally in said tubular member, said pipe having a discharge end located between said deflecting cone and said grinder, openings in said tubular member and in said frustro-conical wall permitting water from said pipe to pass into said compartments, a discharge opening at the opposite end of said tubular member remote from said grinder, means for collecting ore from said discharge opening of said tubular member, said means including a trough, having a sloping bottom and an outlet at the lowest part of the bottom.

6. In an ore mill of the character described including a rotatable grinder and discharge grating at the discharge end of said grinder, radiallyarranged compartments on the discharge end of said grinder, said compartments connected with said grinder'by said grating, a peripheral screen extending about said compartments, means located below said screen for collecting ore particles passing through said screen, a central tubular member attached to and in axial alinement with said grinder extending from said end of said grinder, a discharge port in each compartment connecting with the interior of said tubular member, whereby ore particles which are too large to pass through said peripheral screen will be discharged into said tubular member, means in said tubular member cooperating with said ports to direct material entering therethrough away from said compartments, said means including a conical surface, the apex of said conical surface extending away from said compartments and grinder, radial veins on said conical surface and a ring member in axial alinement with said conical surface extending across the outer edges of said veins near theapex of said conical surface, a discharge opening at the opposite end of said tubular member remote from said grinder, means for collecting ore from said discharge opening of said member and for separating oil? larger particles of ore for return to said grinder.

'7. In an ore mill of the character described including, a rotatable grinder and discharge grating at the discharge end of said grinder, radiallyarranged compartments on the discharge end 0! said grinder, said compartments connected with said grinder by said grating, a peripheral screen extending about said compartments, means'located below said screen for collecting ore particles passing through said screen, a central tubular member attached to and in axial alinement with said grinder extending from said end of said grinder, a discharge port in each compartment connecting with the interior of said tubular member, whereby ore particles which are too large to pass through said peripheral screen will be discharged into said tubular member, means in said tubular member cooperating with said ports to direct material entering therethrough away from said compartments, said means including a conical surface, the apex of said conical surface extending away from said compartments and grind er, radial veins on said conical surface'and a ring member in axial alinement with said conical surface extending across the outer edges of said veins near the apex of said conical surface, a water pipe extending longitudinally in said tubular member, said pipe having a discharge end located between said ports and said grinder, holes in said tubular member and in the walls of said compartments for delivering water to said compartments from said pipe, a discharge opening at the opposite end of said tubular member remote from said grinder, means for collecting ore from said discharge opening of said tubular member and for separating ofi larger particles of 'ore for return to said grinder.

CLYDE 0. SMITH. 

